Expansion of the nation's services sector slowed more than expected last month to weigh the markets down during the midday with the Dow slipping 35 points to 13,233. Nasdaq dropped 27 points to 3032.

On the upside

Zillow (Nasdaq: Z) reversed year ago losses to post a better than expected profit for the first quarter as revenue doubled. Separately, the company announced that it will pay $40 million in cash to acquire RentJuice

Health Net (NYSE: HNT) narrowed first quarter losses but the results fell short of analyst expectations and the company cut its full year guidance.

In the broad market, declining issues outpaced advancers by a margin of more than 5 to 3 on the NYSE and by more than 5 to 2 on Nasdaq. The Russell 2000 which tracks small cap stocks dropped 9 points to 809.